JP-A-08-114034 and JP-A-08-114035 disclose a motor drive type reinforcing bar binding machine provided with: a binding wire feeding mechanism for feeding a binding wire (wire) while bending the wire in a loop-like shape to hang around a reinforcing bar; and a binding wire twisting mechanism for twisting to bind a binding wire wound around the reinforcing bar, and carrying out 1 cycle of binding operation by continuously executing a binding wire feeding operation and a binding wire twisting operation by an operation of a trigger.
Further, Japanese patent No. 3050369 discloses a reinforcing bar binding machine in which a wire reel is provided with indication means indicating a kind of a wire, the reinforcing bar binding machine is provided with means for detecting the wire kind indication means of the wire reel, and means for controlling a torque of twisting a wire in accordance with a kind of the wire, the kind of the wire is detected by the detecting means, and the wire twisting torque is automatically set to a suitable value in accordance with the kind of the wire by the control means.
In the reinforcing bar binding machine, the determination of the kind of the wire is carried out as one element of initializing operation of the reinforcing bar binding machine, when the wire reel is charged to the reinforcing bar binding machine and power source is applied, the control portion feeds the wire by a certain predetermined length by driving a biding wire feeding mechanism at a low speed, and a front end of the wire passes a binding wire cutting mechanism arranged at a vicinity of a nose. During rotating the wire reel at the low speed, wire information indication portion provided at the wire reel is detected by detecting means of the reinforcing bar binding machine.
Although it is general that the wire reel used in the reinforcing bar binding machine is formed by a plastic material in view of formability and cost. However, in the wire reel made of plastic, a wire binding state is changed and a dimension of a bearing hole of the wire reel is varied, by outer air temperature or the like.
Therefore, when dimensions of a reel holding shaft of the reinforcing bar binding machine and the bearing hole of the wire reel are made to be substantially the same, there is a concern that the wire reel cannot be freely be rotated and therefore, the bearing hole of the wire reel is made to be slightly larger than a diameter of the reel holding shaft portion. Therefore, when the wire is drawn out at low speed and the wire reel is rotated at low speed at initializing operation of the reinforcing bar binding machine, there is a case in which the wire reel is fluctuated transversely and a center shaft of the wire reel is displaced from a center of rotation to be rotated by so-to-speak swinging rotation, so that the wire kind information provided at the wire reel cannot be read.